Aldosterone-stimulated sodium uptake by apical membrane vesicles from A6 cells

• Published in: The Journal of biological chemistry 1984-09, Vol.259 (18), p.11221-11225
• Main Authors: Sariban-Sohraby, S, Burg, M B, Turner, R J
• Format: Article
• Language: English
• Subjects: Aldosterone - pharmacology; Amiloride - pharmacology; Animals; Biological and medical sciences; Biological Transport, Active; Cell Line; Cell Membrane - metabolism; Cell physiology; Epithelium - metabolism; Fundamental and applied biological sciences. Psychology; Kidney - metabolism; Membrane and intracellular transports; Membrane Potentials; Molecular and cellular biology; Osmolar Concentration; Sodium - metabolism; Xenopus laevis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)90850-1

Sodium fluxes in plasma membrane vesicles prepared from the cultured toad kidney epithelial cell line A6 are studied. The vesicles are enriched 7-10 times in apical membrane markers. Sodium uptake is osmotically sensitive and inhibited by low concentrations of amiloride (K0.5 = 7 X 10(-8) M at 1 mM NaCl). Vesicles prepared from aldosterone-treated cells (4.5 h at 10(-7) M aldosterone) show a 2-fold enhancement of amiloride-sensitive sodium flux relative to appropriate controls. The above observations are in good agreement with studies of sodium transport across the apical membrane of intact A6 epithelia. Thus, the amiloride-sensitive sodium transporter in the apical membrane of these cells is preserved in the vesicle preparation, making it possible to study the effects of aldosterone in the absence of nonmembrane-related phenomena.